An ordinary seaman (OS) is a member of the deck department of a ship. The position is an apprenticeship to become an able seaman, and has been for centuries. In modern times, an OS is required to work on a ship for a specific amount of time, gaining what is referred to as "sea time". For centuries, the term ordinary seaman was used to refer to a seaman with between one and two years' experience at sea, who showed enough seamanship to be so rated by their captain. Historically, in some navies and the merchant marine, a sailor with less experience was called a landsman.
Ordinary seaman
AB's were in high demand during World War II.
Image: Ordinary seaman chipping
Image: Ordinary seamen swabbing deck
An able seaman (AB) is a seaman and member of the deck department of a merchant ship with more than two years' experience at sea and considered "well acquainted with his duty". An AB may work as a watchstander, a day worker, or a combination of these roles. Once a sufficient amount of sea time is acquired, then the AB can apply to take a series of courses/examinations to become certified as an officer.
Able seamen generally serve as a ship's helmsmen, relying on visual references, compasses, and a rudder angle indicator to steer a steady course as directed by the mate or other officer on the bridge.
Dayworker AB preparing a mast for painting
Knowing how to safely work aloft to maintain cargo rigging is a skill required of an AB.
ABs were in high demand during World War II.
